I always ask free energy people to provide me with their power bills. I am always refused. The power bill tells the story. The following is an extract from a story in Australia where someone installed a Tesla Power-Wall and 6.5kw of solar panels in Australia. His energy bill was reduced 92% or over a $2000 per year saving.
Given the cost of energy storage is rapidly dropping this is a feasible option for many people, especially in rural areas where the cost of connection to the grid is far more expensive than an off grid system.
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Tesla’s assault on household power bill
Mr Pfitzner, a programmer from Sydney’s northwest, his wife and two children were the first to have a Tesla Powerwall version 1 system installed in Australia, and therefore the first capable of a full year’s analysis of use during all seasons.
He gave us five Energy Australia bills covering 426 days up to February 17, 2016, the changeover date, and another five from Diamond Energy from that date covering 350 days. Because of the unevenness of these time periods, amounts were converted to per day values for a comparison.
On the surface there’s no comparison. His five Energy Australia bills totalled $2578.26. His five Diamond Energy bills after Powerwall was installed totalled $178.71; that’s way less than a single Energy Australia bill.
The figures include three discounts of $35 for referring customers to Diamond and 9 per cent Energy Australia early payment discounts. Diamond Energy charged a regular service fee, and offered a 6 per cent discount and a renewable energy reward worth under $10 each bill. Overall, he claims a 92 per cent bill drop. If you exclude the three referrals worth $105, the drop is 89 per cent — still impressive.
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The other main factor is energy savings. With Powerwall installed, the Pfitzners returned more power to the grid than they used in every billing period. They consumed 1349.83 kilowatt hours worth $277.91 and sold back 3807.40kWh worth $304.59.
Pre-battery, the family used on average 23kWh per day; with the battery installed, usage dropped to almost 4kWh of grid power daily. Mr Pfitzner said the battery generated 13-14kWh and, when you add the 4kW from the grid, you had about 17kWh daily. He attributes the 6kWh saving from pre-battery days as “becoming more efficient through knowing what I use”.
He was exporting on average almost 11kWh back to the grid daily and being paid for it. That’s equivalent to half his daily pre-battery usage being returned. The trick was to maximise the amount of power that he uses directly from the solar panels. Basically, when he’s not using solar power directly, he stores it, and when storage is full, he sells energy back to the grid.